The Anomalous Temporal Behaviour of Broadband Lyα\alpha Emission During Solar Flares From SDO/EVE

Despite being the most prominent emission line in the solar spectrum, there has been a notable lack of studies devoted to variations in Ly$\alpha$ emission during solar flares in recent years. However, the few examples that do exist have shown Ly$\alpha$ emission to be a substantial radiator of the total energy budget of solar flares (on the order of 10%). It is also a known driver of fluctuations in earth's ionosphere. The EUV Variability Experiment (EVE) onboard the Solar Dynamics Observatory now provides broadband, photometric Ly$\alpha$ data at 10 s cadence with its Multiple EUV Grating Spectrograph-Photometer (MEGS-P) component, and has observed scores of solar flares in the 5 years since it was launched. However, the MEGS-P time profiles appear to display a rise time of tens of minutes around the time of the flare onset. This is in stark contrast to the rapid, impulsive increase observed in other intrinsically chromospheric features (H$\alpha$, Ly$\beta$, LyC, C III, etc.). Furthermore, the emission detected by MEGS-P peaks around the time of the peak of thermal soft X-ray emission, rather than during the impulsive phase when energy deposition in the chromosphere - often assumed to be in the form of nonthermal electrons - is greatest. Given that spectrally-resolved Ly$\alpha$ observations during flares from SORCE/SOLSTICE peak during the impulsive phase as expected, this suggests that the atypical behaviour of MEGS-P data is a manifestation of the broadband nature of the observations. This could imply that other lines and/or continuum emission that becomes enhanced during flares could be contributing to the passband. Users are hereby urged to exercise caution when interpreting broadband Ly$\alpha$ observations of solar flares. Comparisons have also been made with other broadband Ly$\alpha$ photometers such as PROBA2/LYRA and GOES/EUVS-E.Comment: Submitted to A&A Research Notes, 5 pages 4 figure

Suborbital Platforms as a Tool for a Symbiotic Relationship Between Scientists, Engineers, and Students

Sounding rockets started in-situ space experimentation over 60 years ago with scientific experiments replacing warheads on captured V- 2 German rockets. Prior to this, and still today, suborbital platforms such as airplanes and high-altitude balloons have provided advantageous remote sensing observations advancing many areas of Earth and Space science. There is still a place for first-rate science in both stand-alone missions as well as providing complimentary measurements to the larger orbital missions. Along with the aforementioned science, the cost effectiveness and development times provided by sub-orbital platforms allows for perfect hands-on and first rate educational opportunities for undergraduate and graduate students. This talk will give examples and discuss the mutually beneficial opportunities that scientists and students obtain in development of suborbital missions. Also discussed will be how the next generation of space vehicles should help eliminate the number one obstacle to these programs - launch opportunities

New Observations of Solar Plasma Variability from the Solar Dynamics Observatory (SDO)

The launch of the Solar Dynamics Observatory (SDO) in February 2010 now allows for continuous observations of the Sun on all times scales from seconds to years. The variations in the solar plasma on these time scales cause significant deviations in the Earth and space environments on similar time scales, such as affecting the densities and composition of particular atoms, molecules, and ions in the atmospheres of Earth and other planets. Presented and discussed will be examples of initial results from SDO that show how different temperature plasmas (from 50,OOOK to 20MK+), corresponding to different solar features in the solar atmosphere, evolve and change during solar eruptive events. The presentation will emphasize how the Solar Dynamics Observatory (SDO), the first satellite in NASA's Living with a Star program, has already improved upon current observations and how it will continue provide further insights into the variable Sun and its Heliospheric influence

Solar Plasma Variability Observations from the Solar Dynamics Observatory

The launch of the Solar Dynamics Observatory (SDO) in February 2010 allows for continuous observations of the Sun on all times scales from seconds to years. These variations in the solar plasma cause significant deviations in the Earth and space environments on similar time scales, such as affecting the atmospheric densities and composition of particular atoms, molecules, and ions in the atmospheres of the Earth and other planets. Presented and discussed will be examples of initial results using the data from SDO that show how we can trace the origins of solar activity from inside the Sun using different wavelengths, and therefore different temperatures (from 50,OOOK to 20MK+) that cover the atmosphere and plasma temperature range of the solar atmosphere. The presentation will emphasize how the Solar Dynamics Observatory (SDO), the first satellite in NASA's Living with a Star program, is going to improve upon current observations and provide further insights into the variable Sun and its Heliospheric influence

FISM 2.0: Improved Spectral Range, Resolution, and Accuracy

The Flare Irradiance Spectral Model (FISM) was first released in 2005 to provide accurate estimates of the solar VUV (0.1-190 nm) irradiance to the Space Weather community. This model was based on TIMED SEE as well as UARS and SORCE SOLSTICE measurements, and was the first model to include a 60 second temporal variation to estimate the variations due to solar flares. Along with flares, FISM also estimates the tradition solar cycle and solar rotational variations over months and decades back to 1947. This model has been highly successful in providing driving inputs to study the affect of solar irradiance variations on the Earth's ionosphere and thermosphere, lunar dust charging, as well as the Martian ionosphere. The second version of FISM, FISM2, is currently being updated to be based on the more accurate SDO/EVE data, which will provide much more accurate estimations in the 0.1-105 nm range, as well as extending the 'daily' model variation up to 300 nm based on the SOLSTICE measurements. with the spectral resolution of SDO/EVE along with SOLSTICE and the TIMED and SORCE XPS 'model' products, the entire range from 0.1-300 nm will also be available at 0.1 nm, allowing FISM2 to be improved a similar 0.1nm spectral bins. FISM also will have a TSI component that will estimate the total radiated energy during flares based on the few TSI flares observed to date. Presented here will be initial results of the FISM2 modeling efforts, as well as some challenges that will need to be overcome in order for FISM2 to accurately model the solar variations on time scales of seconds to decades

Reconstructing the Solar VUV Irradiance Over the Past 60 Years

Actual observations of the solar spectral irradiance are extremely limited on climate time scales; therefore, various empirical models use solar proxies to reconstruct the actual output of the Sun over long time scales. The Flare Irradiance Spectral Model (FISM) is an empirical model of the solar irradiance spectrum from 0.1 to 190 nm at 1 nm spectral resolution and on a I-minute time cadence. The goal of FISM is to provide accurate solar spectral irradiances over the vacuum ultraviolet (VUV: 0-200 nm) range as input for ionospheric and thermospheric. A brief overview of the proxies used in the FISM model will be given, and also discussed is how the Solar Dynamics Observatory (SDO) EUV Variability Experiment (EVE) will contribute to improving FISM estimates and its accuracies. Also presented will be a discussion of other solar irradiance proxies and measurements, and their associated uncertainties, used for solar spectral reconstructions

Solar EUV Variability from FISM and SDO/EVE During Solar Minimum, Active, and Flaring Time Periods

The Living With a Star (LWS) Focus Science Team has identified three periods of different solar activity levels for which they will be determining the Earth's Ionosphere and Thermosphere response. Not only will the team be comparing individual models (e.g. FLIP, T1MEGCM, GLOW) outcome driven by the various levels of solar activity, but the models themselves will also be compared. These models all rely on the input solar EUV (0.1 -190 nm) irradiance to drive the variability. The Flare Irradiance Spectral Model (FISM) and the EUV Variability Experiment (EVE) onboard provide the Solar Dynamics Observatory (SDO) provide the most accurate quantification of these irradiances. Presented and discussed are how much the solar EUV irradiance changes during these three scenarios, both as a function of activity and wavelength

Solar Cycle 24 Behavior and Progress on FISM Version 2 Product

Solar cycle 24 has continued to increase in activity towards its peak expected in late 2013. The updated NOAA/SWPC solar cycle prediction as well as the outlook for solar activity during the MAVEN 1-Earth-year mission will be presented. Also presented will be a status updated on the progress of the Flare Irradiance Spectral Model (FISM) version 2 product, which will be a deliverable for the MAVEN mission as it will provide the full solar spectrum from 0.1-190 nm at 0.1 nm spectral resolution and 1-minute temporal resolution based on the three EUV diodes from the MAVEN LPW JEUV instrument

Lyman Alpha Spicule Observatory (LASO)

The Lyman Alpha Spicule Observatory (LASO) sounding rocket will observe smallscale eruptive events called "Rapid Blue-shifted Events" (RBEs) [Rouppe van der Voort et al., 2009], the on-disk equivalent of Type-II spicules, and extend observations that explore their role in the solar coronal heating problem [De Pontieu et al., 2011]. LASO utilizes a new and novel optical design to simultaneously observe two spatial dimensions at 4.2" spatial resolution (2.1" pixels) over a 2'x2' field of view with high spectral resolution of 66mAngstroms (33mAngstroms pixels) across a broad 20Angstrom spectral window. This spectral window contains three strong chromospheric and transition region emissions and is centered on the strong Hydrogen Lyman-a emission at 1216Angstroms. This instrument makes it possible to obtain new data crucial to the physical understanding of these phenomena and their role in the overall energy and momentum balance from the upper chromosphere to lower corona. LASO was submitted March 2011 in response to the ROSES SHP-LCAS call

Decay Phase Cooling and Inferred Heating of M- and X-class Solar Flares

In this paper, the cooling of 72 M- and X-class flares is examined using GOES/XRS and SDO/EVE. The observed cooling rates are quantified and the observed total cooling times are compared to the predictions of an analytical 0-D hydrodynamic model. It is found that the model does not fit the observations well, but does provide a well defined lower limit on a flare's total cooling time. The discrepancy between observations and the model is then assumed to be primarily due to heating during the decay phase. The decay phase heating necessary to account for the discrepancy is quantified and found be ~50% of the total thermally radiated energy as calculated with GOES. This decay phase heating is found to scale with the observed peak thermal energy. It is predicted that approximating the total thermal energy from the peak is minimally affected by the decay phase heating in small flares. However, in the most energetic flares the decay phase heating inferred from the model can be several times greater than the peak thermal energy.Comment: Published in the Astrophysical Journal, 201